【摘要】 采用人工模拟降雨方法,研究坡度10°,15°和雨强60,120,180mm/h条件下,盖度为0,33%,67%和88%的香附子对南方红壤坡面的减沙效应及其水动力学机理。研究结果表明:香附子在红壤坡面具有良好的减沙作用,盖度为33%的香附子平均能够减少72%的土壤侵蚀;随着植被盖度的增加,土壤侵蚀量减少,减沙率增大。雨强越大,红壤坡面的植被减沙率越大。相同盖度植被的减沙率在15°坡面较在10°坡面小。香附子能够降低坡面流的流速和弗劳德数,增大达西—韦斯巴赫阻力系数。植被盖度越大,流速越小,弗劳德数越小,达西—韦斯巴赫阻力系数越大,盖度为88%的坡面的达西—韦斯巴赫阻力系数约是裸坡的7倍。坡面流流速可以通过水流能坡的0.5次幂、单宽流量0.33次幂的乘积来拟合,拟合方程的系数能够反映植被对坡面粗糙度的影响。坡面的达西—韦斯巴赫阻力系数随着植被盖度呈指数函数显著增加。植被盖度越大,土壤的抗冲性越强,植被盖度为88%的坡面的土壤临界剪切力约是裸坡的2.5倍。更多还原

【Abstract】 Adopting the method of simulated precipitation,aquantitative study was made on the mechanisms of grass in controlling the slope erosion in the Sothern China.The experiments were designed with different slopes(10°and 15°),rainfall intensities(60,120 and 180 mm/h),and different vegetation coverage of Cyperus rotundus(0,33%,67% and 88%)in the Rainfall Simulation Hall of the Laboratory of Red Soil Erosion and Flow Hydraulic on the South China in Guangzhou City,Guangdong Province.The results showed that the Cyperus rotundus could effectively control soil erosion on the red soil slope.About 72% of soil erosion was reduced by the grass with 33%coverage,and the efficiency of Cyperus rotundus in reducing soil erosion increased with increasing grass coverage.Under the experimental condition,the efficiency of Cyperus rotundus in reducing soil erosion was greater under higher rainfall intensities,and was smaller on the 15°slopes than on 10°slopes.The grass could reduce flow velocity and the Froude number and increase the Darcy-Weisbach friction coefficient.The flow velocity and the Froude number decreased with the increasing vegetation coverage;and the Darcy-Weisbach friction coefficient increased with the increasing vegetation coverage.The Darcy-Weisbach friction coefficient on the slopes with 88%coverage was about seven times of those on bare slopes.The flow velocity can be fitted by the product of 0.33 power of the discharge per unit width and 0.5power of the surface slope.The fitting coefficient could reflect the influence of the vegetation on the roughness of the slope.With the increase of vegetation coverage,the resistance coefficient of slope increased significantly following an exponential function.The soil resistance to erosion increased by the vegetation,and the critical shear stress value of soil with 88%coverage was 2.5times of the value of the bare soil.更多还原